在英语中，当某人去刷牙时，可以用以下几种方式来表达：
"He is brushing his teeth."
Brush是一个动词，意思是刷牙。
例句：
He brushes his teeth twice a day. 他每天刷两次牙。
"He is brushing his teeth with toothpaste."
Toothpaste是一个名词，意思是牙膏。
例句：
He always uses a toothbrush and toothpaste to brush his teeth. 他总是用牙刷和牙膏刷牙。
"He is going to the bathroom to brush his teeth."
Bathroom是一个名词，意思是浴室。
例句：
He goes to the bathroom to brush his teeth every morning. 他每天早上都会去浴室刷牙。
"He is cleaning his teeth."
Clean是一个动词，意思是清洁，所以当某人去刷牙时，也可以用clean来表示。
例句：
He always cleans his teeth before bed. 他总是睡觉前刷牙。
"He is brushing his teeth."
Brush是一个动词，意思是刷牙。
例句：
He brushes his teeth twice a day. 他每天刷两次牙。
"He is brushing his teeth with toothpaste."
Toothpaste是一个名词，意思是牙膏。
例句：
He always uses a toothbrush and toothpaste to brush his teeth. 他总是用牙刷和牙膏刷牙。
"He is going to the bathroom to brush his teeth."
Bathroom是一个名词，意思是浴室。
例句：
He goes to the bathroom to brush his teeth every morning. 他每天早上都会去浴室刷牙。
"He is cleaning his teeth."
Clean是一个动词，意思是清洁，所以当某人去刷牙时，也可以用clean来表示。
例句：
He always cleans his teeth before bed. 他总是睡觉前刷牙。